The present invention relates to a spring guide rail with several centering fingers and a bottom rail for the guidance of the vane lifting springs and for the stroke limitation of the vanes of a rotary vane-type machine. The spring guide rail is shaped from a one-piece sheet metal strip, into which strip recesses of an essentially rectangular shape are punched so as to form a ladder-type structure with two longitudinal bars and with cross bars. From this ladder-type structure the spring guide rail is formed by means of repeated folding operations around longitudinal axes of the ladder-type structure, with the longitudinal bars of the ladder-type structure forming the two parts of the bottom rail and the cross bars forming the centering fingers.
In rotary vane-type machines, radially outwardly directed guide grooves are provided in a rotor and working vanes are arranged in these grooves. Compression springs supporting themselves at the bottom of the groove press the working vanes radially outwardly against a cam curve surrounding the rotor. The compression springs are arranged on the centering fingers of a spring guide rail so that the centering fingers penetrate the interior of the compression springs. The spring guide rail supports itself at the bottom of the groove by means of a bottom rail. The spring guide rail further limits the inward movement of the working vane by means of a mechanical stop.
A spring guide rail of the type referred to above is known from the German Patent DE-OS 1,653,923. In the spring guide rail disclosed therein the cross bar sections folded to face each other to form the centering fingers rest against each other. It is a disadvantage that the centering fingers have a rectangular transverse cross-section since an insufficient guide for the compression springs is provided thereby due to the circularity of the interior space of the compression springs. The centering fingers, and thus the spring guides further may easily be deformed upon the abutting action of the vane which will lead to operational disturbances up to total failure of the machine.